Solar cells are often used in the form of solar modules, in which they are arranged in rows and columns. Sufficient voltage for the consumer is generated by connecting the solar cells in series in the solar module. However, if part of the solar module is in shadow, there is a risk that the shadowed cells may be destroyed due to the serial connection, because in this case they function as electrical consumers. The individual solar cells in the solar module should therefore be protected from overvoltages in the reverse direction by bypass diodes.
However, it is not possible to connect the individual solar cells to bypass diodes in monolithically interconnected modules (MIM) in an unlimited manner. Monolithic, series-connected solar modules include a great number of solar cells which are applied as a layer sequence to a common, semi-insulating substrate. The individual solar cells are separated from each other by trenches in the layer sequence and connected to each other via integrated metal contacts. One example of an MIM solar module and a method for producing such a module is described for example in the publication by S. van Riesen et al., “GaAs-Monolithically Interconnected Modules (MIMS) with an Efficiency above 20%”, 19th European Photovoltaic Solar Energy Conference, 7-11 Jun. 2004, Paris. The individual photovoltaically active surfaces of the solar cells of such a solar module are normally very narrow, having a width of about 1 mm to limit the current strength in strong light. They are therefore highly suitable for use in concentrator systems, for example parabolic mirror and shape concentrators. Until now however, when single cells in monolithically series-connected solar modules were connected to bypass diodes, it was necessary to sacrifice a significant amount of active receiving surface in order to integrate the bypass diodes in the solar module between the solar cells. The performance capability of the diodes in such an arrangement was also limited.
Even the species-related U.S. Pat. No. 6,600,100 B2 or US 2004/0163698 A1 only describe arrangements in which the bypass diodes are located either on or beside the photovoltaically active layers.
The object of the present invention is to suggest an arrangement of a solar cell having a bypass diode that enables improved performance capability of the bypass diode and results in reduced loss of active receiving surface when it is integrated in a solar module.